Synergistic stimulation of HIV-1 rev-dependent export of unspliced mRNA to the cytoplasm by hnRNP A1 1 1Edited by A. R. Fersht

Najera, I S; Krieg, Marion; Karn, Jonathan

doi:10.1006/jmbi.1998.2473

Cited by 59 publications

(48 citation statements)

References 68 publications

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“…By using a UV cross-linking technique, a previous study did not identify hnRNP F and 2H9 in the same complex as hnRNP A1 and the 50-kDa protein, here characterized as hnRNP H (34). As in the case of WA1, the GGG motif is again essential for the assembly of hnRNP H family members onto an RNA substrate.…”

Section: Resultsmentioning

confidence: 66%

“…Interestingly, the INS sequence has been shown to be a specific binding site for both hnRNP A1 and for an unknown protein of 50 kDa (34). When the INS is substituted with the hnRNP A1 high affinity WA1 sequence, the new viral substrate RNA retains the synergistic stimulation of Rev-dependent transport (34). The INS sequence contains a GAUGGGA element that when mutated disrupts the binding of both hnRNP A1 and the 50-kDa protein.…”

Section: Resultsmentioning

confidence: 99%

“…The INS sequence contains a GAUGGGA element that when mutated disrupts the binding of both hnRNP A1 and the 50-kDa protein. This disruption also inhibits the INS activity of the sequence (34). Given the sequence similarity between the INS and the WA1 sequence GAUAGGGA (with an extra A residue relative to the INS sequence), hnRNP H is a candidate to be the 50-kDa protein.…”

Section: Resultsmentioning

confidence: 99%

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Determination of the RNA Binding Specificity of the Heterogeneous Nuclear Ribonucleoprotein (hnRNP) H/H′/F/2H9 Family

Caputi

Zahler

2001

Journal of Biological Chemistry

188

176

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Members of the heterogeneous nuclear ribonucleoprotein (hnRNP) H protein family, H, H, F, and 2H9, are involved in pre-mRNA processing. We analyzed the assembly of these proteins from splicing extracts onto four RNA regulatory elements as follows: a high affinity hnRNP A1-binding site (WA1), a sequence involved in Rev-dependent export (p17gag INS), an exonic splicing silencer from the ␤-tropomyosin gene, and an intronic splicing regulator (downstream control sequence (DCS) from the c-src gene. The entire family binds the WA1, instability (INS), and ␤-tropomyosin substrates, and the core-binding site for each is a run of three G residues followed by an A. Transfer of small regions containing this sequence to a substrate lacking hnRNP H binding activity is sufficient to promote binding of all family members. The c-src DCS has been shown to assemble hnRNP H, not hnRNP F, from HeLa cell extracts, and we show that hnRNP 2H9 does not bind this element. The DCS contains five G residues followed by a C. Mutation of the C to an A changes the specificity of the DCS from a substrate that binds only hnRNP H/H to a binding site for all hnRNP H family members. We conclude that the sequence GGGA is recognized by all hnRNP H family proteins.Some proteins of the heterogeneous nuclear ribonucleoprotein (hnRNP) 1 class were initially described as components of a nucleosome-like structure that protects and organizes nascent RNA polymerase II transcripts (1-3). Our understanding of hnRNP functions has broadened from this purely structural vision to include multiple aspects of mRNA biogenesis such as transcription, splicing, capping, polyadenylation, nuclear transport, and mRNA stability. More than 30 hnRNPs have been identified so far. Many hnRNPs have a modular structure characterized by one or more RNA binding domains and by one or more auxiliary domains that are frequently enriched in a few amino acids, mainly glycines. The RNA recognition motif (RRM), the arginine-rich motif, the KH domain, and the RGG box are some of the main motifs that are found in hnRNP proteins (4).The precise roles of hnRNP proteins in gene expression are likely to be reflected by their RNA binding specificity. Therefore, it is important to have a clear understanding of the RNA binding specificities and affinities of the different family members. Early studies demonstrated that several hnRNPs have affinities for immobilized ribohomopolymers such as poly(G) bound by hnRNPs E, H, F, and M, poly(C) bound by hnRNPs K and J, and poly(U) bound by hnRNPs C and M (5). Subsequently, several hnRNPs were observed to bind specific RNA sequences by UV-mediated cross-linking. Furthermore, utilizing a selection and amplification approach from pools of random RNAs, high affinity binding sequences for hnRNPs A1 (6) and C (7), have been identified. The binding properties of hnRNP A1 are the best characterized so far. Several reports (1, 8 -12) have shown that hnRNP A1 and other members of the hnRNP A/B group (hnRNP A1b, A2, and B1) share common RNA substrate specificities...

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Section: Resultsmentioning

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Determination of the RNA Binding Specificity of the Heterogeneous Nuclear Ribonucleoprotein (hnRNP) H/H′/F/2H9 Family

Caputi

Zahler

2001

Journal of Biological Chemistry

188

176

View full text Add to dashboard Cite

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“…hnRNP A1 was shown to act synergistically with Rev to contribute to nucleocytoplasmic transport of RRE-containing HIV-1 RNAs. 23 The capacity of hnRNP A1 relied on the presence of an hnRNP A1-binding site within the INS in the N-terminal Matrix domain of HIV-1 Gag. 23 Additional roles for hnRNP A1 and other hnRNPs in retroviral splicing regulation rely largely on their ability to bind sequences adjacent to and within splicing enhancer and negative splicing regulatory sequences.…”

Section: Introductionmentioning

confidence: 99%

“…23 The capacity of hnRNP A1 relied on the presence of an hnRNP A1-binding site within the INS in the N-terminal Matrix domain of HIV-1 Gag. 23 Additional roles for hnRNP A1 and other hnRNPs in retroviral splicing regulation rely largely on their ability to bind sequences adjacent to and within splicing enhancer and negative splicing regulatory sequences. 18,24,25 These roles in retroviral RNA splicing and nucleocytoplasmic ReseARch PAPeR trafficking might also be functionally linked 26 a notion that is supported by newer work that shows that several functionally distinct hnRNPs interact with Rev.…”

Section: Introductionmentioning

confidence: 99%

Depletion of hnRNP A2/B1 overrides the nuclear retention of the HIV-1 genomic RNA

et al. 2013

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hnRNP A2 is a cellular protein that is important for nucleocytoplasmic and cytosolic trafficking of the hIV-1 genomic RNA. Both hnRNP A2's interaction with hIV-1 RNA and its expression levels influence the activities of Rev in mediating nucleocytoplasmic export of the hIV-1 genomic RNA. While the lack of Rev expression during hIV-1 gene expression results in nuclear retention of hIV-1 genomic RNA, we show here by fluorescence in situ hybridization and fractionation studies that the genomic RNA translocates to the cytoplasm when hnRNP A2/B1 are depleted from cells. Polyribosome analyses revealed that the genomic RNA was shunted into a cytoplasmic, dense polyribosomal fraction. This fraction contained several RNA-binding proteins involved in viral gene expression and RNA trafficking but did not contain the translation initiation factor, eIF4G1. Amino acid incorporation into nascent polypeptides in this fraction was also greatly reduced, demonstrating that this fraction contains mRNAs that are poorly translated. These results demonstrate that hnRNP A2/B1 expression plays roles in the nuclear retention of the hIV-1 genomic RNA in the absence of Rev and in the release of the genomic RNA from translationally inactive, cytoplasmic RNP complexes.

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Influence of the Small Leader Exons 2 and 3 on Human Immunodeficiency Virus Type 1 Gene Expression

et al. 2001

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The human immunodeficiency virus type 1 (HIV-1) uses an elaborate alternative splicing pattern for the generation of both the 1.8-kb as well as the 4-kb classes of mRNA. An additional diversity of transcripts in both classes is created by the optional inclusion of the small exons 2 and 3 in the leader sequence. To analyze a possible influence of these leader exons on HIV-1 gene expression, several series of expression vectors with different leaders were constructed, expressing either Rev and Env or a heterologous coding sequence, i.e., the chloramphenicol acetyl transferase (CAT) ORF. Transfection experiments of HeLa-T4(+) cells revealed for all series of constructs that mRNA as well as protein expression was stimulated by the presence of exon 2 and reduced by exon 3. The function of the leader exons 2 and 3 is neither dependent on the regulatory proteins Tat or Rev nor on viral coding sequences. Neither transcription rates nor stability of polyadenylated RNAs were found to be responsible for the different levels of steady-state mRNA. When either exon 2 or 3 was inserted into a heterologous intron, processing of the primary transcripts generated identical mRNA species while maintaining the differences in exon 2/3-dependent mRNA steady-state levels. These results may be explained by exon-specific nuclear RNA degradation rates, as also indicated by results from an in vitro degradation assay using a HeLa nuclear extract.

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Synergistic stimulation of HIV-1 rev-dependent export of unspliced mRNA to the cytoplasm by hnRNP A1 1 1Edited by A. R. Fersht

Cited by 59 publications

References 68 publications

Determination of the RNA Binding Specificity of the Heterogeneous Nuclear Ribonucleoprotein (hnRNP) H/H′/F/2H9 Family

Determination of the RNA Binding Specificity of the Heterogeneous Nuclear Ribonucleoprotein (hnRNP) H/H′/F/2H9 Family

Depletion of hnRNP A2/B1 overrides the nuclear retention of the HIV-1 genomic RNA

Influence of the Small Leader Exons 2 and 3 on Human Immunodeficiency Virus Type 1 Gene Expression

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